Although crinoids are generally considered to be passive suspension feeders, Silurian echinoderms may have had rather varied modes of feeding.

By analogy with living stalked crinoids many Paleozoic forms with long pinnulate arms, such as Dimerocrinites and Macrostylocrinus, are interpreted as having formed filtration fans. Modern crinoids are "leeside" suspension feeders; that is, they recurve the backsides of their arms into the strongest water currents. Water flushes through the spaces between pinnules and forms a low-pressure zone on the other side where the ambulacral grooves are amply supplied with sticky tube feet. Particles spiraling in these eddies are captured on the tube feet and propelled into the cilia-lined food groove; a combination of food and mucous then makes its way to the mouth, like the flow from various branches coming together like tributaries of a stream drainage systems. Camerate crinoids, such as Macrostylocrinus and Dimerocrinites, may have fed in approximately this way, although the lack of muscular articulations in their arms, in contrast to modern articulate crinoids, must have limited arm mobility. An intriguing discovery came from the excavations at Caleb Quarry: complete specimens of the crinoid Catatonocrinus halli (Figures 244 and 245) revealed, for the first time, the arm structure of this remarkable, rare crinoid. Catatonocrinus was almost unique among the disparid crinoids in possessing pinnulate arms, the large number of small side branches provided a relatively large surface area for food gathering.

Densely pinnulate arms do appear to have been efficient to food capture, but only if sufficient currents existed in the environment to force water through the relatively dense meshwork of arms and pinnules. Such crinoids are often thought to be restricted to high-energy environments, but the Rochester Shale crinoids seem to contradict this. Most of the densely pinnulate camerate crinoids and Catanonocrinus, which are preserved almost in life position, evidently did not inhabit high-energy environments as they occur in mudstones. Evidently they were able to collect enough food even without strong current flushing and in fact they appear to have been successful in quite a range of environments.

Although modern crinoids have yielded much insight into crinoid feeding behavior, it is evident that not all Paleozoic crinoids could have formed efficient parabolic feeding fans. Most of the small disparid crinoids, such as Homocrinus, most calceocrinids, and myelodactylids(Figures 283, 244 and 264 - 268), lacked pinnules, possessed low flexibility, stick-like arms, and may have used large sticky tube feet to capture particles from low energy water. Flexible crinoids like Lecanocrinus and Icthyocrinus (Figures 261 - 263 and 255 - 260b) had broad, space-filling brachials in the arms that ended in tendril like branches, but lacked pinnules. Their arms are often preserved as tightly coiled, like a clenched fist. It has been suggested that these crinoids were raptorial, actively capturing larger plankton with their flexible arms and pulling it into the mouth.

Most blastozoans such as the callocystitid cystoids and Stephanocrinus lacked arms and instead had tiny coiled, thread-like brachioles. These were so slender that there was little or no space for tube feet and it has been suggested that these organisms lacked tube feet altogether (Sprinkle, 1973). If so, they must have fed in a very different way than crinoids, perhaps using mucous secretion and cilia to trap microplankton. The small size of their food collecting appendages may have confined these organisms to higher energy or more food-rich shallower environments. These are among the groups that do not extend into Rochester deeper water environments and they may have required shallower more agitated settings.

Caryocrinites is an exception that tests the general rule. This cystoid convergently evolved elongate appendages resembling crinoid arms (Figures 311 - 324). They are not made of evolutionarily related (homologous) parts. The arm plates are actually cystoid ambulacral floor plates, which normally run along the surface of the theca, as in the Rochester Shale genus Callocystites (Figures 338 - 344) and their apparent "pinnules" are actually brachioles homologous to those seen in the callocystitids. Nonetheless, Caryocrinites had much greater food gathering capabilities than other cystoids, such as Callocystites. This may have given Caryocrinites great versatility and, indeed, this cystoid occurs in a broader range of environments than do most blastozoans or short-armed crinoids.